Fuel supply system



J. c.- MCALVAY 2,330,066

FUEL SUPPLY SYSTEM Sept. 21, 1943;

Filed Feb, 24, 1941 Patented Sept. 21, 1943 FUEL SUPPLY SYSTEM John C. McAlvay,

ster Electric Company,

ration of Delaware Racine, Wis., asslgnor Web- Racine, Wis., a eorpo- Application February 24, 1941, Serial No. 380,403 2 Claims. (01. 158-28) The present invention relates to fuel supply systems, and is particularly concerned with an improved time delay system to prevent the admission of fuel oil to the burner nozzle until a draft is well established.

One of the objects of the invention is to provide an improved fuel supply system including a time delay circuit of such characteristics that when the main burner control closes the circuit energizing the motor driving the fan (which provides air for combustion), and driving the fuel pump, and energizing the ignition circuit, a time delay interval occurs before oil is admitted to the burner nozzle.

Another object of the invention is the provision of an improved fuel supply system in which it is impossible for fuel oil nozzle until a suitable time has elapsed for the draft to be established by the fan which supplies air for fuel combustion so as to prevent objectionable smoking and vibration, which might otherwise occur, due to imperfect combustion.

Another object of the invention is the provision of an improved fuel supply system in which liquid fuel supplied to the burner nozzle is delayed so as to eliminate the possibility of an accumulation of liquid fuel in the fire pot or the supply of liquid fuel to the burner draft and ignition have been suitably established.

If the burner nozzle is supplied with liquid fuel too early in the cycle of ignition of the burner, the atomized fuel may be sprayed on the already hot parts of the fire pot, and may become vaporized, so that an explosion may occur when the ignition circuit is energized, or due to the lack of a suitable amount of air at that time, much smoke may be produced, with the resultant pufllng and vibration of the furnace.

Another object of the present invention is the provision of a simple, yet effective, circuit control for a fuel pump of the class described, by means of which the supply of oil to the burner nozzle may be delayed until the draftand ignition conditions are perfectly established to insure best conditions of combustion.

Another object of the invention is the provision of a fuel supply system of the class described. which is dependable, economical, and capable of being used for a long period of time without necessity for replacement or repair of its parts.

Another object of the invention is the provision of an improved fuel supply 'system including a solenoid operated valve in which the solenoid'is so arranged that it has a delayed action and is enernozzle before conditions of,

, itself may be energized from the ordinary alterto be supplied to the burner nating current supply line.

Other objects and advantages of the invention will be apparent from the following description and the accompanying drawings, in which similar characters of reference indicate similar parts throughout the several views.

Referring to the single sheet of drawings accompanying the specification,

Fig. 1 is a vertical sectional view, showing the parts of a fuel pump and controlling elements for the liquid fuel, adapted to be embodied in the invention;

Fig. 2 is a wiring diagram of the system.

Referring to Fig. 1, It! indicates in its entirety the fuel unit, which is adapted to be driven by a motor ll (Fig. 2), and which is connected to drive the pumpshaft l2 rotatably supported by the housing l3.-

The fuel pump in question may be substantially as disclosed in the prior Patent No.

2,145,404 of Herbert C. Osborne, issued January 31, 1939, filed August 13, 1937, which is hereby incorporated by reference thereto.

This fuel pump is'of the type having two sets of gears l5, l6, and l1, ill to provide a two-stage pump. The gears l5, l6 pump up the liquid fuel from the tank and keep a constant supply of fuel in a reservoir l9, which surrounds the pump assembly, and the excess of fuel flows back through the conduit 20 into another chamber 2| that is in communication, through a return pipe 22, with the tank.

The gears l1, l8 comprise the high pressure stage of the pump, and they take in liquid fuel from the reservoir l9 and discharge it through an outlet port 23 into a valve chamber 24, which is in communication with the reservoir chamber l9 through the conduits 25, 26 controlled by the needle valve 21.

The needle valve 21 is engaged by a compression coil spring 28, which in turn reacts against gized by direct current, although the system the core armature 29 of a solenoid III in such manner that when the core 29 is in the position of Fig. 1 the valve opening 25 is closed by the needle valve 21.

The plunger or needle valve 21, is also urged upward by a coil spring 32, sufficient to lift the plunger 3|, spring 28, and the solenoid core 29, when the solenoid 30 is deenergized. Thus'the valve opening 25 'will be open when the solenoid is de-energized, but when the solenoid is energized its core 29 is pulled downward piston 3|, which supports the The tension of the coil spring 32 is until it reacts sufliciently on the spring 28 to compress the spring 32 and close the valve opening 25. The ports 25 and 26 are in the nature of by-pass ports, permitting the liquid fuel under pressure from the high pressure stage l1, IE to be by-passed back into the reservoir l9, when the valve 21 is open; but when the valve is closed the high pressure stage l1, l8 supplies fuel under pressure to the usualfuel regulator valve, and thus to the oil burner nozzle.

Referring now .to Fig. 2, the solenoid valve is again indicated by 30, and the motor which drives the fuel pump, and which may also drive the blower for supplying air for combustion is indicated by the.numeral The circuit preferably includes a vacuum tube rectifier of the type commercially designated as 117 Z6, which consists of a full wave high vacuum rectifier of the heater cathode type, the heater being rated at 117 volts, so that it may be energized by ordinary house current type voltage. The tube is indicated in Fig. 2 by the numeral 33. 34 indicates the burner controlling devices, such as stack thermostats, room thermostats, and safety devices, which may turn on the electric current, energizing the motor II to drive the pump and the blower, These controlling devices may be energized from the ordinary 110 volt lighting supply circuit, the conductors of which are indicated at 35 and 36.

From the controlling devices 34 the conductor 31' leads to the terminal 1 of the rectifier tube, which is one of the heater terminals, This conductor is thereby connected to the two filaments 38 and 39 in series, the latter having its opposite terminal connected to the terminal 2, and is connected by the conductor 40 to the supply conductor 4|. Terminal 2 is connected to conductor 39 by conductor 52.

The tube is preferably connected as a half wave rectifier, that is, it has its plates tied together and its cathodes tied tigether in order to take advantage of the double current carrying capacity of the tube when connected in this way. The plate voltage of the tube may be supplied from the alternating current source through the solenoid coil 30. Thus the solenoid 30 is connected in circuit by a conductor 42 leading to the terminal 1 of the tube, and its other terminal is connected by a conductor 43 to the terminals 3 and of the tube, which are the terminals leading to the plates 44, 45.

As previously stated, the heater filaments 38, 39 may be supplied directly from the A. C. line: The cathodes 46, 41 may be connected to the conductor 4| through the terminals 8 and 4, respectively, by conductors 48 and 49, the conductor 48 being connected to conductor 40. The motor II is connected by conductor 50 to the conductor 3'! and by the conductor 5| to the conducfor 40. Thus the motor is supplied with current through the conductors 4| and 31.

The motor is in parallel with the filaments of the tube and the plate supply of the tube, while the coil 30 is in series with the plate supply,

The circuit through the motor from line may be traced as follows: 31, 50, 5|, 40, 4|.

The operation of the system is as follows: When the fuel burner is turned off by the controls 34, so that the motor pump, and blower are standing still, the by-pass valve 25 is open, because the solenoid is de-energized, and the spring 32 is of sufficient strength to lift the valve and the core 29. When the control circuit is closed by controlling devices at 34, the motor circuit is immediately energized, and the pump and motor immediately start rotating.

After a predetermined period of time, the pump will build up a suitable pressure at its discharge outlet, and the air fan will provide a suitable supply of air for combustion, but fuel will not be supplied to the nozzle until the solenoid 30 is energized as follows.

The rectifier tube 33 is also connected to the energizing circuit 31, 4| at the same time as the motor; but when the cathode of the tube is cold, there is no electron flow in the tube and no current passesin the plate circuit of the tube.

As soon as the tube is energized, the heater filaments 38 become hot, but it takes a predetermined period of time to heat up the cathodes 46, 41. As the cathodes are heated, the electron 'current increases until there is suflicient current passing to actuate the solenoid 30, which is connected in the plate circuit, and is only energized when the plate circuit is passing suflicient current.

The energization of the solenoid 30 causes its core 23 to be drawn down until the parts are in the position of Fig. 1, with the valve opening 25 closed. The closing of this by-pass valve from the outlet of the high pressure stage to the reservoir 9 permits the pump to supply fuel under pressure to the usual regulator valve which controls the pressure of the fuel supplied to the burner nozzle.

As described in the patent to Osborne, above referred to, this regulator valve also requires a short time for the building up of pressure, and thereafter fuel under predetermined pressure is supplied to the burner nozzle, and the excess is by-passed back to the tank or to the intake of the P p.

Another advantage of the present system is that the solenoid is energized by direct current, which is advantageous because of the more dependable operation of such a system under these conditions. Great difficulty has been encountered in obtaining satisfactory operation of solenoid valves operated on alternating current, particularly when the load on the needle is high, due to 'a high setting of the pressure regulating valve. These difficulties are not encountered when the solenoid is energized by direct current according to the present system, which operates in a satisfactory and dependable way.

It will thus be observed that a time interval is provided for the draft to be perfectly established and for ignition conditions to be at their best, before fuel is supplied to the burner nozzle.

The solenoid is not actuated until the rectifier tube is heated up sufficiently to pass a plate current of sufficient magnitude to actuate this solenoid. This heating up period of the tube is utilized to provide the time delay required.

Thus the objectionable smoking and vibration or putting, which might otherwise occur at the ignition of the fuel, when the burner is turned down, due to imperfect combustion, is eliminated. and fuel is not supplied until the conditions for combustion are perfectly established.

My fuel supply system is dependable, and in the event of the failure of operation of the rectifier tube it is safe because the fuel will never be supplied unless the rectifier tube is operative.

While I have illustrated a preferred embodiment of my invention, many modifications may be made without departing from the spirit of the invention, and I do not wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a fuel supply system, the combination of a motor adapted to drive a blower for combustion and a fuel pump with electric means for controlling the outlet of fuel from said fuel pump to a burner nozzle, and a rectifier tube of the indirectly heated cathode type having its plate circuit connected to energize said electric means and controlling means for energizing simultaneously said rectifier tube and said motor whereby suitable draft conditions are first established by the operation of the motor and blower, but the supply of fuel to the burner nozzle is cut off by said electric means until the rectifier tube becomes heated and passes suflicient plate current to actuate said electric means.

2. In a fuel supply system, the combination of a motor adapted to drive a blower for combustion and a fuel pump with electric means for controlling the outlet of fuel from said fuel pump to a burner nozzle, and a rectifier tube of the indirectly heated cathode type having its plate circuit connected to energize said electric means and controlling means for energizing simultaneously said rectifier tube and said motor whereby suitable draft conditions are first established by the operation of the motor and blower, but the supply of fuel to the burner nozzle is cut off by said electric means until the rectifier tube becomes heated and passes sufficient plate current to actuate said electric means, said electric means comprising a solenoid actuated by-pass valve adapted to by-pass the pressure output of the pump until said valve is closed.

JOHN C. MCALVAY. 

